Interview: The potential link between physical activity and recurrence in breast cancer survivors
Editor's note: The following is an excerpt of an interview with Jennifer A. Ligibel, MD, instructor of medicine at Harvard Medical School. She and her colleagues found a potential relation between exercise and a significant decrease in insulin levels and hip circumference in breast cancer survivors.
We performed this study because there is a growing amount of observational evidence that women who exercise after being diagnosed with breast cancer have a lower risk for recurrence. There was a report from another large study that came out recently that showed the same thing: Women who are physically active after having breast cancer had about a 50% lower recurrence risk compared with women who were inactive, and this has been observed now in three large studies.
Nobody understands what really happens during exercise that could be influencing recurrence rates. So the point of our study was to look at what happens, hormonally, when women become physically active. Specifically we looked at insulin, which is a hormone involved in diabetes and blood glucose regulation, but has also been shown to be a mitogen. Higher insulin levels have also been related with higher recurrence risks in patients with breast cancer.
There is probably a lot that happens when people begin to exercise that may influence cancer recurrence risks and we are at the cusp of figuring out how something like physical activity affects breast cancer recurrence risk. All the evidence so far that has shown recurrence is lower has been observational. Eventually we will need to not only figure out what happens when people begin to exercise, but really show through randomized trials that it is exercise that is making the difference and not something else that these women are doing.
We are a step away from an actual recommendation for patients with breast cancer. Data from many observational studies suggest that physical activity is a good thing for women who have had breast cancer. We all know that we should be exercising more for a variety of different reasons.
The results from another study recently showed that women with early stage breast cancer are more likely to die of other causes than die of breast cancer. There are many beneficial things that occur when women exercise, but most oncologists do not spend time talking to their patients about physical activity.
We are hoping that eventually as we can demonstrate that being physically active after having breast cancer can improve your odds for survival and exercise will become part of the treatment regimen for breast cancer patients. – Interview by Paul Burress